This invention relates generally to crash sensors for use in vehicles equipped with airbags. More specifically, the invention relates to the placing of the crash sensors.
The present invention also constitutes an improvement over co-assigned U.S. Pat. Nos. 4,284,863, 4,329,549, 4,573,706 and 4,580,810, the disclosure thereof being incorporated therein by reference in accordance with accepted legal principles.
U.S. Pat. Nos. 4,284,863 and 4,329,549 are damped ball-in-tube crash sensor designs.
In U.S. Pat. No. 4,573,706, there is disclosed and claimed a mechanical sensor with a low bias for mounting within a vehicle passenger compartment which is operable without electric power for igniting the pyrotechnic elements of an airbag safety restraint system where the sensor comprises a sensor train which includes a sensing mass, a spring bias, a firing pin and a primer; and means responsive to sustained acceleration primer and initiate airbag inflation.
U.S. Pat. No. 4,580,810 discloses and claims an airbag system adapted to be mounted on the axis of a steering wheel of a vehicle wherein the sensor is mounted inside an inflator for the airbag. This system includes an inflatable airbag; a gas generator having a housing and ignitable gas-generating material contained therein in fluid communication with the interior of the bag which is external to the housing. The system also includes ignition means for igniting the gas-generating material which is within the housing and a sensor also mounted within the housing of the gas generator for sensing the crash and initiating the ignition means.
It is known that when mounting a sensor on the steering column of a vehicle, the sensor normally rotates with the steering column and thus in order for the sensor to have the same orientation regardless of the angle of the steering column, the sensor axis must be parallel to the axis of the steering column. The inventor's research has shown that the steering column mounted sensors frequently fired earlier than other passenger compartment mounted sensors having the same calibration. This would found to be caused in some cases by the coupling of the steering column with the crush zone of the vehicle. In other cases, the steering column was not coupled with the crush zone but still the sensor fired early; the crush zone being that portion of the vehicle which experiences a velocity change early in the crash before the entire vehicle has slowed down. The inventor's study concluded that placing a crash sensor at an angle to the horizontal makes it additionally more sensitive due to the vertical accelaration components present in a vehicle crash.